Grinding roll for flour mills



Ucit. M 19%., 11,51%,842

.l SCHMIDT GRINDING ROLL FOR FLOUR MLLS Filed June 13. 1925 LUDWIGSCHMIDT, F ST. LOUIS, MISSOURI, ASSIGNOR-TO ESSMUELLER FUR- NISHINGCOMPANY, 0F ST. `LOUIS, MISSOURI, A. CORPORATION `OIE MISSOURI.

GRINDING ROLL FOB FLOR MILLS.

application inea rune 1a, was. serial no. 645,169.

To all lwhom it may conce/rn: v

Be it known that ll, LUDWIG SCHMIDT, a citizen ofthe United States,residing in the city of St. Louis and State of Missouri, t have inventednew and useful Improvements in Grinding Rolls for Flour Mills, of whichthe following is a specification.

This invention relates to grinding rolls and a method of preparing thesurfaces of i0 the same.

lln the reduction of wheat to flour, corrugated rolls are employed inreducing the grain down to a `certain stage in which midlings areproduced, the corrugated rolls being usually referred to as the breakrolls. The middlings'are composed of the `hard granular portion of thegrain, and the finer grades of flour are made from them. fn theirreduction, smooth rolls are employed. 'llhe ordinary arrangementofgrinding or reducing rolls involves two rolls set in close proximityto each other, one of the rolls being-runat a slightly increased speedrelative to the other.

Originally, in 'the reduction of middlings, smooth and highly polishedrolls were employed. lt'was soon found, however, that notwithstandingthe differential rate of speed at which the rolls were run, the brokenparticles of grain did not pass readily between the rolls, as the latterwere too smooth to bite or engage the particles of grain andl cause themto pass between the rolls.

'llofovercome this disadvantage, rolls having very fine corrugationswere substituted for the smooth rolls, atv least at the head of themiddlings reduction system. Not only are the finest practicablecorrugations in such a roll too coarse to reduce the middlings in themanner desired, but it has been found to be almost impossible to secureaccurate or uniform corrugation of the roll, due to mechanical reasonsnot necessary to set forth here.

To obviate the use 'of finely corrugated rolls, a method was devised forproducing rolls with a dull finish instead of the highly polishedsurface which had previously characterized the smooth roll. rlFhedulliinish -roll has been very extensively used, and, while it is animprovement over the polished roll, or the corrugatedfroll, it stillpresents 'the objection of being too smooth to cause the properengagement and feed of the grain -particles between the rolls.

According to thls invention, i ll provide for imparting a Very finedegree of scratchmg to the surface of theroll, so that while its surfaceis relatively much rougher than that of a rollwith a dull finish, suchsurface is much smoother .than that of a roll having the yfinest degreeof corrugation which `it has been found practicable to produce.

According to one way of practicing my invention, t e off by an emerywheel in the usual manner, Thereafter, ll apply to the surface of theroll the flat side of a relatively small wheel of any suitable abrasivematerial, 'such as emery, carborunduln, or the like, the plane of thevside of the wheel applied to the roll forming a tangent with theperiphery of the roll, and the axis of said Wheel lying at an angle to aplane cutting the axis of the roll. The roll is then revolved andsimul-V taneously moved endwise through the medium of a lead-screw, andthe grinding wheel in contact with the surface of the roll is alsosimultaneously revolved, with the result that the entire surface of theroll is subjected to the abrasive or grinding action of the wheel. Thesurface of the roll will, by this means, be scratched in a uniformmanner, the coarseness of the abrasions produced on the surface of theroll corresponding, of course, tothe coarseness of the grain of thematerial of the grinding Wheel. V'llhe scratched surface of the rollwill present a series of Wave-like or billowy formations, which changein appearance and relative location according to the angle of vision,and the character and extent of which may be varied by varying theinclination of the axis of the grinding Wheel relative to a [selectedplane cutting the axis of the roll.

Such method of scratching the surface of the roll possesses theadvantage that itmay be performed with relative rapidity. The scratchingof the surface by grinding leaves the roll true throughout its entiresurface, as the roll is not subjected to a bending pressure, as is thecase where it is attempted to corrugate the roll. Furthermore, as therelative positions of the roll and grinding disk are fixed during theoperation, and as surface ofthe roll is smoothed ico , vanced in ahorizontal plane, the myriads of ing a portion of lines scratched on thesurface of the roll, or the iguresformed by said lines, are caused Ytoprogressively overlap, or intersect, each other, so that no one portionof the surface of the roll can, by any possibility, receive a greaterdegree` of abrading action than an-v other portion.

A further advantage of this system of scratching the surface of the rollis that the scratched lines have a general curvilinearextensionlengthwise of the roll, or, in other words, parallel with theaxis of the roll, as distinguished from an extension approximatingarallelism with the direction of rotation o the roll, so that themaximum frictional engagement of the surface lof the roll with the grainparticles is thereby afforded.

In order that a correct idea may be gained of the degree of scratchingemployed, it may be stated that to the casual touch or feeling of theroll, its surface would appear smooth, the scratched lines beingexceedingl mi'- nute, and the depth of the abrasion in imal in extent.

In order that the invention may be fully understood, I have illustrated,in the accompanying drawings, an arrangement of apparatus by meansofwhich the surface of a grindin roll may be etched inthe manner -hereinescribed.

In said drawings- Figure 1 is a cross-sectional View through a grindingmachine provided with the means which I employ for practicing myimproved method of finishing the surface of the roll Figure 2 is a viewin front elevation showa roll with a grinding disk applied thereto, thelatter being sectioned frgm the rest of the grinding mechanism; an iFigure 3 is a View on an enlarged scale illustratin a portion of thesurface of the roll after 1t has been scratched according to my'method.'Ihis illustration, however, is suggestive rather than technicallyaccurate.

Referrin now to the drawings, the numeral 1 in icates the bed of agrinding Inachine of ordinary construction, the upper sidevof whichprovides guide-ways 2, on which is -slidably mounted a carriage 3, whichis provided at its upepr ends with uprights 4, provided with the usualmeans for rotatably supporting a roll 5w Said means itesinvolves arotatable head having a pulley 6, by means of which the roll 5 may berotated through the medium of a belt 7. The carriage 4 is provided onits underside with a depending casting-8, which has, at its lower end,an interiorly screw-threaded 'bearing 9, which is in screw-threaded enagement with the lead-screw 10, extending ongitudina-.lly of the machineand rotated in the usual way to cause the carriage 4 to travel back andforth en the ways 2.

Extending from the rear of the bed 1 is a bracket 11, which supportsstandards l2, having rotatably mounted in their upper ends an emeryvwheel 13, driven by a belt 14 and pulley 15, and which is movable intoand out of Contact with the object to be ground.

So far, the machine described is of the usual construction and involvesno element of novelty. Heretofore, the practice has been to mount theroll 5 on the bed 1 and to move .the same back and forth over the ways 2while its surface was in contact with the rapidly rotating emery wheel13; .This resulted in imparting a smooth surface to the roll 5, andunless special means were utilized to impart a dull finish to thesurface of the roll, the treatment with the emery wheel would result inimparting a high degree of polish to theroll. After the rollhas beensmoothed by the emery wheel 13, the latter is moved out of contact withthe surface of the grinding roll 5, and the surface of the latter isthen finished according to the method of the present invention.

`For the purpose of practicing my improved method, I mount on the frontof the machine, centrally of its length, a bracket 16, in which aremounted four or more adjusting screws 17 which support, at their upperends, a frame 18, having rotatably mounted therein a spindle 19, onwhich is secured, between the side members of the frame, a pulley 20,and at its ends, a grinding wheel 21. The pulley is driven from anysuitable source of power by a belt 22. The height of the frame 18relative to the axis of the roll 5 may be varied by adjusting the heightof said screws. Nuts 23, on screws 17, support the base of the frame 18,and act also as clamping members. I also provide means for permittingthe inclination of the axis of the spindle 19 relative to the axis ofthe roll 5 to be varied, and, in the present instance, this is effectedby forming rounded heads 24 on the ends of the screws 17 which engage inlarge apertures 25 in the base of the frame 18. By lowering or raisingone or the other of the screws, or by raising one and lowering theother, the angle of inclination of the spindle 19 to the axis of theroll 5 can be changed at will, as will be understood.

The construction illustrated for permitlll animee ting the adjustmentot' the height and angular inclination of the frame 18 is more or lessconventional,- and it will be understood that any preferred way ofmounting the frame 1S may be employed.

ln applying the grinding .wheel 21 to the surface of the roll 5, thepla-ne ot the operative face ot the grinding Wheel, indicated by theline 26, is positioned at 'right angles to a radius 27 of the roll 5,forming an angle with a plane cutting the anis of said roll, and theheight of the grinding Wheel is so adj usted that its line of contactwith the surtace of the roll, indicated by the line 28, in Figure 2, isbetween its periphery and axial center. The length of this line ofsurface contact between the grinding Wheel and roll may be varied fromzero, the periphery of the grinding disk, to the maximum, which would bethe line of contact between the surface of the roll and the Jface of thegrinding disk, passing through the center of the inding disk.' In suchcase, of course, the nll Width of the grinding disk would then be inengagement with the surface of the grinding roll. in this latterposition, the grinding disk would operate to scratch circular lines onthe surface of the roll, owing to the symmetrical arrangement of thecenters of the two rotating members.

ln order to prevent this result, and to produce curved lines more nearlyapproximating to straight lines than to circular lines, l use a line ofcontact between the tace ot the disk and the surface of the roll, which,as stated, is between the periphery und center of the grinding disk. lnpreterence, the length of this line is approximately one and one-halftimes the length oi the pitch ot the threads of the lead-screw l0,

and l adjust the angle of inclination of the axis oi the Wheel to theanis of the roll so that the line of contact between the face of thegrinding Wheel and the Surface of the roll is at right angles to aradius of the roll, forming an angle with a. plane cutting the anis ofthe roll. .f

The relative speeds oi rotation of the roll and grinding Wheel 2l may bevaried at will, it being understood, of course, that the grinding wheel2l rotates at a much higher rate of speed than the roll 5.

With apparatus arranged as described, the belts T and 22 are driven torotate the roll 5 and grinding wheel 2l, the grinding disk if?. haringpreviously been moved out of contact *with the roll 5. The lead-screwis, of course. simultaneously rotated, with the result that the roll 5is both rotated about its axis and moved longitudinally thereof. .fitthe completion of the movementk of the roll in one direction, themachine is reversed and the roll moved in the opposite direction, stillin contact with the grinding Wheel 21, and this operation may be rep lor four times. At the completion ot the eration, the surface of the rollWill have an appearance' similar to that illust 1 i Figure 3.

A roll having a surface of this character is ideal for the purpose ofreducing middlings, as it is rough enough to engage and cause the promptpassage Without slipping of the particles of grain between the rolls,and not suiiciently rough to causey the disintegrating orugrindingaction produced by corrugated ro s.

@ne of the decided advantages of my invention is the element of economy,both as to time and apparatus involved. i roll may have its surfacenished, according to my' method of procedure, on the average, in fromfifteen to twenty minutes, and, of course, the provision and mounting ofthe grinding Wheel is a matter of ineonsiderable expense.

The character of the grinding Wheel may be varied according to thedegree of coarse ness of the scratching desired on the roll, and anycharacter ot abrasive material, found suitable for the purpose, may beused in the composition of said wheel.

While l have shown and described the roll as being rotated andsimultaneously moved longitudinally, While the grinding 'Wheel is simplyrotated it will be obvious that 'he roll could simply be rotated, Whilethe grinding wheel was both rotated and moved longitudinally. ln otherWords, it is immaterial to the invention which of these members is movedlongitudinally relative to the other.

l claim:

l. A cereal grinding roll having as its n entire surface provided withextended and distinct lines of relatively short length ground-scratchedtherein.

3. .il roll for milling Wheat having its entire surface provided withdistinct lines ci scratches having a general longitudinal extension andof irregular length.,

4. L roll for milling Wheat having its entire surface provided withdistinct lines of scratches having a general longitudinal extension andof relatively short length and irregular arrangement..

5l. A roll for milling Wheat having its entire surface provided withdistinct lines 0i scratchesA the said lines of scratches beingcurvilinear and of relatively short length and having a generalextension longitudinal of the rollu ln testimony whereof, l havehereunto set my hand.

Lnnvvio. scin'r.

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